Coupling

ABSTRACT

A coupling which comprises two clamping members insertable into the open-ended chamber of a first element and two locking members located between the clamping members and having hooks extending through an aperture provided in a wall of a second element. A bolt can move the locking members apart to thereby urge the clamping members against the first element and to engage the hooks with that side of the wall which faces away from the chamber. The clamping members and the locking members are provided with cams and followers or analogous tensioning devices which cooperate to urge the hooks toward the clamping members when the locking members move apart whereby the wall is pressed against the clamping members and/or against the first element.

United States Patent [72] Inventor Johannes Jankowski v Campione dltalia, Lago di Lugano Vita Totone 17, Italy [21] Appl. No. 759,386 [22] Filed Sept. 12, 1968 [45] Patented Apr. 13, 1971 [32] Priority Jan. 26, 1968 [33] Germany [31 .135593 [54] COUPLING 29 Claims, 12 Drawing Figs.

[52] U.S.Cl 287/54, 287/ 124 [51] int. Cl 'F16b 7/04 [50] Field ofSearch 287/l89.36

(C), 54 (A), 54 (B), 54 (C), 2, 124, 56

[56] References Cited UNITED STATES PATENTS 2,855,255 l0/1958 Sonderstrup 287/54(B) 2,941,855 6/1960 Weill 287/54(C) 3,338,602 8/1967 Arnd 287/2 3,458,052 7/1969 Kann 287/54(A) FOREIGN PATENTS 96,260 6/1960 Norway 287/20.92C

403,207 6/ 1966 Switzerland 287/124 Primary ExaminerThomas F. Callaghan Assistant Examiner-Andrew V. Kundrat Att0rney-Michael S. Striker ABSTRACT: A coupling which comprises two clamping members insertable into the open-ended chamber of a first element and two locking members located between the clamping members and having hooks extending through an aperture provided in a wall of a second element. A bolt can move the locking members apart to thereby urge the clamping members against the first element and to engage the hooks with that side of the wall which faces away from the chamber. The clamping members and the locking members are provided with cams and followers or analogous tensioning devices which cooperate to urge the hooks toward the clamping members when the locking members move apart whereby the wall is pressed against the clamping members and/or against the first element.

PATEN TEB APR 1 3197! SHEET 1 BF 5 Fig.2

Inventor J 0/74 IWUES wwzoum muaeLLSA- 46 0/77! COUPLING BACKGROUND OF THE INVENTION The present invention relates to couplings in general, and more particularly to improvements in couplings which can establish separable or permanent connections between identically or differently dimensioned and/or configurated structural elements. Still more particularly, the invention relates to couplings which can be utilized to establish connections between rods, bars, tubes, pipes, cylinders, sleeves, hollow or solid profiled stock, flat bodies and/or other types of elements which can form component parts of furniture, scaffolds, room dividers, shelves, racks, frames and/or many others,

It is already known to employ in the manufacture of furniture couplings of the type which are installed in one element and comprise movable locking members adaptedto engage another element and to thus establish a connection between the two elements. A drawback of such couplings is that the connections are unstable, i.e., the two interconnected elements are normally free to pivot, wobble or to otherwise move relative to each other. This is undesirable when a coupling is used to connect parts of chairs, beds, sofas, tables or other pieces of furniture. Moreover, all components or many components of conventional couplings must be machined or otherwise finished with a high degree of precision, and the same applies for the dimensioning and finish of elements which are connected to each other by such couplings. This is especially necessary when a conventional coupling is employed in assembling parts of frames cannot mirrors, panels or the like. Also, presently known couplings cannot compensate for deviations in dimensions of structural elements from a given norm.

Certain other types of conventional couplings employ eccentrics, screws or bolts which must be driven into or moved firmly against the structural elements to thereby insure the establishment of rigid and reliable connections between two or more elements. A drawback of such couplings is that, in order to properly hold a screw or bolt or to resist the pressure of an eccentric, the walls of the structural elements must have a certain minimum thickness and a certain minimum rigidity which automatically eliminates such couplings from use in connection with a wide variety of parts. Moreover, the holes or bores for the screws or bolts must be drilled and tapped at predetermined locations which contributes to the manufacturing cost and necessitates the use of precision tools. It is often difficult or impossible to drill holes at the locale of use, especially if the elements which are to be joined by a coupling cannot be cut to size at the manufacturing plant. Proper determination of the location of holes, recesses or the like at the place of assembly necessitates the use of complicated equipment and must be carried out by skilled labor in a time'consuming operation.

SUMMARY OF THE INVENTION It is an object of my invention to provide a novel and improved coupling which can be used to establish rigid connections between prefabricated parts, which can be installed and/or taken apart in a manufacturing plant or workshop as well as at the locale of use by resorting to simple and readily available tools, and which can be used for connection of rugged, bulky and thick-walled as well as of lightweight and thin-walled structural elements.

Another object of the invention is to provide a coupling which is designed in such a way that the force with which two or more elements are connected to each other can be changed at the will of the operator and which can compensate for at least some inaccuracies in the machining and/or dimensioning of elements which are being connected to each other.

A further object of the invention is to provide a coupling which can be installed or disengaged by exertion of a small force.

An additional object of the invention is to provide a coupling which may but need not utilize threaded parts and wherein such threaded parts need not engage with the elements which must be connected to each other.

Still another object of the invention is to provide a coupling which can be installed by persons having little experience or skill, which can establish a connection that cannot be readily terminated or weakened in normal use, and which is at least nearly completely concealed when properly installed to furnish a connection between two or more structural elements.

A concomitant object of the invention is to provide a coupling whose components are automatically moved into firm and reliable engagement with each of the two structural elements when the coupling is properly installed and applied to join the elements to each other.

An ancillary object of the invention is to provide a coupling which can be installed or removed within short periods of time.

Briefly stated, the improved coupling is utilized to establish a temporary or permanent connection between a structural element which is provided with an open-ended chamber and an apertured wall adapted to be placed adjacent to the open end of the chamber so that one of its sides then faces away from the structural element. The coupling comprises a clamping unit having two clamping members in the chamber of the structural element (such clamping members may be inserted into or they may form temporarily or permanently fixed or integral parts of the structural element), a locking unit comprising a pair' of locking members disposed between the clamping members and movable between first and second positions in which they are respectively located at a first and at a second distance from each other, the locking members having preferably hook-shaped or claw-shaped front portions insertable through the apertured wall in the first positions and overlying the one side of such wall in the second positions of locking members, actuating means for moving the locking members between the first and second positions, and tensioning means provided on the members to urge the front portions toward the clamping members in response to movement of locking members toward second positions.

The tensioning means may comprise cooperating integral portions of the locking and clamping members, and such portions are preferably remote from the front portions of locking members. For example, the tensioning means may comprise cams provided on the clamping members and followers provided at the rear ends of ocking members and engaging the respective cams, at least during a portion of movement of locking members from first to second positions. Such cams and followers insure that the wall is urged toward the structural element on movement of locking members toward second positions and bears against the front ends of clamping members and/or against the structural element to thus prevent wobbling, pivoting or other undesirable movements of the wall with reference to the structural element or vice versa.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved coupling itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a central longitudinal sectional view of a coupling which embodies one form of my invention and whose parts are shown in a starting position prior to establishment of a rigid but separable connection between two hollow structural elements;

FIG. 2 is a similar central longitudinal sectional view of a second coupling whose parts are also shown in a starting position;

FIG. 3 is a central longitudinal sectional view of two different couplings which are employed to connect two structural elements to a common intermediate element, a portion of a third coupling which connects the intermediate element with a third structural element being shown in front elevational view;

FIG. 4 is a central longitudinal sectional view of a fourth coupling;

FIG. 5 is a central longitudinal sectional view of a fifth coupling;

FIG. 6 is a central longitudinal sectional view of a sixth coupling;

FIG. 7 is a central longitudinal sectional view of a seventh coupling;

FIG. 8a is a central longitudinal sectional view of a further coupling wherein the parts are shown in positions they assume prior to establishment of a rigid connection between two hollow structural elements;

FIG. 8b is a similar sectional view but showing the parts of the coupling in intermediate positions;

FIG. 80 is a similar view but showing the parts of the coupling in their final or operative positions;

FIG. 9a is a perspective view of a first locking member in the coupling of FIGS. 8a8c; and

FIG. 9b is a similar perspective view of a second locking member in the coupling of FIGS. 8a8c.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. I, there is shown a coupling which is employed to establish a rigid but readily separable connection between a first structural element 1 and a wall 10 which forms part of a second structural element 11. The element I is hollow and is provided with an internal chamber 2 at least one end of which is open and which accommodates the two main units 3, 4 of the coupling, The unit 3 is a clamping or retaining unit and comprises two clamping members I2, 13. The other unit 4 is a locking or connecting unit and comprises two locking members 5, 6. The front portions of the locking members 5, 6 form two hooks or claws 7, 8 which extend through an opening or aperture 10a in the front end wall 10 of the structural element 11 and into an internal compartment or chamber 10b of this element. A spreading or actuating member, here shown as a screw or bolt 9, is employed to move the locking members 5, 6 apart and to thereby cause the hooks 7, 8 to engage the inner side of the end wall 10, i.e., that side of the wall 10 which faces away from the open end of the chamber 2. The bolt 9 also causes (indirectly) the locking members 6 to move in a direction to the left, as viewed in FIG. 1 and to thereby form a rigid link between the clamping members 12, I3 and the end wall in order to prevent movements of the element 1 with reference to the element II or vice versa. The elements 1, 11 may constitute two hollow profiled rods or bars which form part of a piece of furniture, for example, two portions of a chair or table. The improved coupling serves to connect the elements I, II to each other in such a way that the end wall 10 is at least substantially normal to the longitudinal direction of the element 1.

The clamping members l2, 13 are of identical size and shape and are loosely connected to each other by a rivet H4 or an analogous fastener. These clamping members respectively comprise straight portions or legs l5, 16 whose rear or inner (left-hand) end portions are suitably bent to be located rather close to each other and to accommodate the shank of the fastener 14. The legs 15, 16 are provided with U-shaped slits and the portions within the confines of such slits are bent to form two inwardly extending substantially V-shaped tensioning cams or abutrnents 17, 18 which are mirror symmetrical with reference to the central longitudinal symmetry plane of the coupling. The faces of the cams l7, 18

are respectively shown at 19 and 20; these cam faces slope inwardly and forwardly, i.e., toward the structural element 11 and can be engaged by abutment or followers 25, 26 adjacent to the rearmost or innennost portions of the locking members 5, 6. The bights of the earns l7, 18 respectively extend into cutouts or windows 23, 24 provided in the locking members 5, 6 in front of the followers 25, 26.

The outer sides of the legs l5, 16 are provided with ribs, serrations, teeth or analogous unevennesses 22 which can penetrate into the adjoining surfaces in the chamber 2 of the structural element 1 to thus prevent lengthwise displacement of the clamping unit 3. Two leaf springs 27, 28 are respectively inserted between the members 5, 12 and 6, 13 to bias the serrations 22 against the adjoining surfaces of the structural element 1 and to simultaneously urge the locking members 5, 6 toward each other, namely, to first positions in which the locking members are disposed substantially centrally between the legs l5, 16 of the clamping members 12, 13.

A sidewall or panel of the element 1 is formed with an opening or aperture 29 which affords access to the slotted head of the actuating bolt 9 so that the latter can be engaged by a suitable tool. The spaces between the aforementioned U- shaped slits of the legs 15, 16 provide additional openingsor apertures 30, 31 the former of which registers with the opening 29 and enables an operator to place the stem of the bolt 9 into mesh with the clamping member 5 which latter is formed with a tapped hole 32. The length of the openings 29, 30 is selected in such a way that the hooks 7, 8 of the locking members 5, 6 can be introduced into the compartment 10b while at the same time enabling the operator to move the hooks 7, 8 into the chamber 2 so that the entire coupling is then accommodated in the element 1. The locking member 5 has a bent over rear end portion of tip 21 which can engage the rear end face of the locking member 6 to move the latter toward the element 11 when the operator engages the bolt 9 and pushes the hook 7 of the locking member 5 through the opening 10a and into the compartment 10b. An internal partition 33 of the element 11 limits the extent to which the hooks 7, 8 can penetrate into the element 11.

The operation is as follows:

In the first step, the main units 3, 4 of the coupling are inserted into the element 1 so that the hooks 7, 8 are accommodated in the chamber 2. The leaf springs 27, 28 bias the locking members 5, 6 to the illustrated first positions. Introduction of the coupling into the chamber 2 can be effected by resorting to a tool which engages the head of the actuating bolt 9 and is caused to push the locking member 5 in a direction to the left, as viewed in FIG. I. The locking member 5 engages the cam 17 of the clamping member 12 and the latter shifts the clamping member 13 by way of the fastener 14. The spring 28 entrains the locking member 6. The element 11 is then placed against or close to the end face of the element 1 and the tool which engages the actuating bolt 9 is causedto push the locking members 5, 6 to the positions shown in FIG. 1, i.e., the hooks 7, 8 are fully accommodated in the compartment 10b. The tip 21 of the locking member 5 engages and pushes the locking member 6 when the bolt 9 is caused to move in a direction to the right. During such shifting, the inner end of the bolt 9 need not engage the locking member 6, i.e., it suffices if the bolt extends into but not beyond the tapped hole 32 of the locking member 5. The hooks 7, 8 are then adjacent to the outer side of the partition 33 in the element 11.

In the next step, the operator rotates the bolt 9 in a sense to move the locking members 5, 6 apart and to thus deform the leaf springs 27, 28, This moves the hooks 7, 8 away from each other and into registry with the inner side of the end wall 10. As the operator continues to rotate the bolt 9, the followers 25, 26 slide along the faces 19, 20 of the cams l7, l8 and cause the locking members 5, 6 to move in a direction to the left so that the books 7, 8 engage the inner side of the wall 10. Such engagement between the hooks 7, 8 and wall 10 takes place after the followers 25, 26 move the clamping members 12, 13 in a direction to the right and into abutment with the outer side of the end wall 10. As the bolt 9 continues to move the locking members 5, 6 away from each other, the followers 25, 26 cause the serrations 22 to penetrate into the element 1 and to thus prevent any lengthwise displacement of the clamping members 12, 13. The inclination of faces 19, 20 on the cams 17, 18 is such that the followers 25, 26 can spread the hooks 7, 8 into registry with the inner side of the end wall 10, that the clamping members 12, 13 are caused to abut against the outer side of the end wall 10, that the hooks 7, 8 engage the inner side of the end wall 10, and that the serrations 22 penetrate into the element 1. This completes the installation of the coupling which then provides a rigid but readily separable connection between the elements 1 and 11.

In order to release or disengage the coupling, the operator simply turns the bolt 9 in a sense to permit the springs 27, 28 to return the locking members 5, 6 to the first positions shown in H6. 1. The hooks 7, 8 then register-with the opening 100 and can be withdrawn from the compartment 10b. In the coupling of FIG. 1, the cams 17, 18 and followers 25, 26 constitute a tensioning device which serves to urge the hooks 7, 8 toward the clamping members 12, 13 in response to rotation of the actuating bolt 9 in a sense to move the locking members 5, 6 away from first positions. This tensioning device is remote from the hooks 7, 8.

The units 3, 4 may consist of metallic or plastic material.

FIG. 2 illustrates a second coupling which provides a separable connection between two hollow structural elements 34 and 35. These elements are of rectangular outline and are joined end to end. The element 35 has an end wall 35a provided with an opening or aperture 35b communicating with an internal chamber or compartment 350. The adjoining end of the chamber 34a in the element 34 is open and one of the sidewalls 54 of the element 34 is provided with an elongated opening or aperture 56.

The coupling of FIG. 2 comprises a clamping unit 36 and a locking unit 37. The clamping unit comprises two clamping members 39, 40 and the locking unit 37 comprises two locking members 46, 47. The front portions of the locking members 46, 47 form hooks 46a, 47a similar to the hooks 7, 8 shown in H6. 1. The rear portions of the clamping members 39, 40 are loosely connected to each other by a fastener 38. The numerals 40a, 41 denote the U-shaped front end portions or tensioning cams of the clamping members 39, 40 and these tensioning cams 40a, 41 are respectively provided with flanges 42, 43 which are substantially normal to the longitudinal direction of the element 34. Furthermore, the cams 40a, 41 have sloping or inclined faces 44, 45 which correspond to the cam faces 19, shown in FIG. 1.

The locking members 46, 47 have followers 48, 49 which can cooperate with the faces 44, 45 of tensioning cams 40a, 41. The inner or rear end portions 50, 51 of the locking members 46, 47 are bent outwardly and away from each other to form retainers for a pair of resilient elements here shown as helical expansion springs 52, 53 operating between the clamping members 39, 40 and the median portions of locking members 46, 47. The springs 52, 53 tend to bias the locking members 46, 47 toward each other to thereby maintain the hooks 46a, 47a at the front ends of these locking members in registry with the opening b. At the same time, the springs 52, 53 bias the serrated or toothed external surfaces of clamping members 39, against the internal surfaces of sidewalls 54 of the element 34.

The locking member 47 has a boss or enlargement which is provided with a tapped hole to take the stem of an actuating bolt 55 whose head is accessible through the aforementioned opening 56 and a registering opening 57 in the clamping member 40.

The operation of the just described coupling is clearly analogous to that of the couplingshown in FIG. 1. When the actuating bolt 55 is rotated in a sense to move the locking members 46, 47 apart (from first to second positions), the followers 48, 49 cooperate with the faces 44, of tensioning cams 40a, 41 to draw the hooks 46a, 47a of the locking members into engagement with the inner side of the end wall 350, to move the flanges 42, 43 into abutment with the outer side of the end wall 35a, and to force the serrations of clamping members 39, 40 into the material of the adjoining sidewalls 54. Thus, the clamping members 39, 40 are rigidly secured to the element 34, the followers 48, 49 urge the flanges 42, 43 against the outer side of the end wall 35a, and the followers simultaneously urge the hooks 46a, 47a of the locking members 46, 47 against the inner side of the end wall 35a to thus prevent any movement of the elements 34, 35 with reference to each other. In this embodiment of my invention, the tensioning device including the cams 40a, 41 and followers 48, 49 is spaced from, but is not very remote from the hooks 46a, 47a. At least one of the clamping members 12, 13 and/or, at least one of the locking members 5, 6 may consist of an elastic material which is deformed in response to movement of locking members from first to second positions.

FIG. 3 illustrates the manner in which two or more hollow profiled structural elements can be connected'to each other through the intermediary of a cubelike or dicelike intennediate or connecting element 62. The illustration shows two profiled structural elements 60, 61 which are connected to each other by way of the intermediate element 62, and this illustration further shows a portion of a coupling which connects the intermediate element 62 with a further profiled structural element similar to the structural element 60or 61.

The couplings which connect thestructural elements 60, 61 to the intermediate element'62 are of identical design and therefore, only one of these coupling (namely, that between the elements6l and 62) will be described in full detail. The intermediate element 62 has six walls each of which is formed with a round inlet opening or aperture 81 adapted to receive the hooks or claws 79, of one of the couplings. Each coupling comprises two U-shaped clamping members 63, 64 and two locking members 73, 74. The clamping members 63, 64 have suitably bent inner or rear end portions 65 which are loosely connected to each other by a fastener 66. The flanges 67, 68 at the front ends of clamping members 63, 64-abut against the outer side of the adjoining apertured wall of the intermediate element 62 when the coupling is in operative position. The rear flanges 69, 70 of the clamping members 63, 64 are adjacent to the end portions 65 and constitute two tensioning cams provided with slots 71, 72 for the followers 75, 76 of the locking members 73, 74, respectively. These followers respectively engage with the camming edges 77, 78 of the tensioning cams 69, 70. The hooks 79, 80 respectively constitute the front portions of the locking members 73, 74. Circular openings or apertures 81 in the walls of the intermediate element 62 are preferred at this time because such aperturescan be readily machined by resorting to available tools or machines. It will be seen that the books 79, 80 are bounded by arcuate (convex surfaces) having radii of curvature similar to the radii of apertures 81.

Helical springs 82, 83 are inserted between the clamping members 63, 64 and the adjoining locking members 73, 74 to bias the hooks 79, 80 toward each other and into registry with the respective aperture 81. Openings or slots 85, 86 in a sidewall of the element 61 and in the clamping member63 permit passage of the stem of an actuating bolt '84 which meshes with the locking member 73 and can move the latter away from the locking member 74 to thereby engage the hooks 79, 80 with the inner side of the adjoining apertured wall of the intermediate element 62 and to cause the followers 75, 76 to slide along the camming edges 77, 78 in order to force the serrated outer sides of clamping members 63, 64 into the adjoining internal surfaces of the structural element 61. The stem of the actuating bolt 84 extends through the openings 85, 86 with at least some clearance.

When the coupling is properly applied, the hooks 79, 80 engage the inner side of the wall of the intermediate element 62, the flanges '67, 68 engage the outer side of such wall opposite the hooks 79, 80, the serrated portions of clamping members 63, 64 engage the adjoining intemal surfaces of the structural element 61, and the springs 82, 83 store energy.

It will be noted that the coupling between the elements 61, 62 can provide a rigid connection between such elements even though the element 61 need not abut against the element 62. In other words, the flanges 67, 68 of the clamping members 63, 64 can extend beyond the open end of the element 61 to bear against the adjoining outer side of the element 62. FIG. 3 further shows that the width of the gap between the elements 60, 62 exceeds the width of the gap between the elements 61, 62. The width of each such gap can be determined in advance by properly selecting the initial axial position of clamping members 63, 64 with reference to the respective element 60 or 61. The openings 85 preferably resemble elongated slots so that they permit lengthwise displacement of actuating bolts 84 and of the remaining parts of corresponding couplings. The surfaces flanking such openings or slots 85 need not take up any stresses. The feature that the couplings of FIG. 3 can be properly applied even if the element 60 or 61 does not abut against the intermediate element 62 is of particular importance in establishment of connections between elements which are not machined with utmost precision. Thus, and particularly since the width of the gap between the elements 60, 62 need not be the same as that between the elements 61, 62, a shorter-than-average element 60 can be properly coupled to the element 62 together with an element 61 of average length.

The heads of actuating bolts 84 need not extend beyond the elements 60, 61. As a matter of fact, and when such actuating bolts are driven home to spread the locking members 73, 74 apart, their heads may be located entirely within the confines of openings 86 in the corresponding clamping members 63.

If the intermediate element is a hollow sphere or a hollow cylinder (i.e., if its outline is circular rather than polygonal), the front faces of flanges 67, 68 on the clamping members 63, 64 can be of concave shape so that they can bear flush against a convex outer side of a spherical or cylindrical intermediate element when the actuating member 84 causes the locking members 73, 74 to the second positions shown in FIG. 3.

The coupling of FIG. 4 is designed to provide an exceptionally strong connection between two structural elements 87, 88, namely, a connection whose strength approximates or even exceeds that of a riveted joint. The difference between this coupling and the previously described couplings is that the leaf springs or helical springs are dispensed with and that the clamping members 89, 90 are mounted in the open-ended chamber of the hollow element 87 in such a way that they cannot be shifted toward or away from the element 88. As shown, the clamping members 89, 90 are respectively provided with outwardly extending projections or protuberances 91, 92 which are received in holes or recesses 93, 94 formed in adjoining walls of the element 87. The front end faces 95 of the clamping members 89, 90 are flush with the end face of the element 87.

The locking members 96, 97 of the coupling shown in FIG. 4 are U-shaped and respectively comprise front flanges or hooks 98, 99 and rear flanges 102, 103 each of which constitutes a follower. The rear followers 102, 103 respectively cooperate with camming edges 104, 105 of the clamping members 90, 89, and the front followers or hooks 98, 99 cooperate with camming edges 106, 107 flanking an opening or aperture 108 in the end wall 880 of the element 88.

The locking member 97 has a tapped hole for an actuating bolt 109 which can be introduced through registering openings 110, 111 respectively provided in a sidewall of the element 87 and in the clamping member 89. When the bolt 109 is rotated in a sense to move the locking members 96, 97 apart, the hooks 98, 99 urge the end wall 88a against the end faces 95 of clamping members 89, 90 and the followers 102, 103 bear against the camming edges 104, 105 to prevent withdrawal of projections 91, 92 from the respective recesses 93, 94. In this embodiment of my invention, the tensioning device comprises the followers 102, 103 and camming edges 104, I05.

It is clear that the clamping members 89, can form integral parts of the element 87 or that they can be permanently or detachably affixed to this element. If the clamping members 89, 90 are integral with the element 87, the latter is simply provided with internal camming edges 104, and with the opening for the actuating bolt 109. If the material of the element 87 is sufficiently rigid,.the front end faces 95 of the clamping members 89, 90 need not abut against the end wall 88a. Furthermore, the position of protuberances 91, 92 and recesses 93, 94 can be reversed, and the connections between the element 87 and clamping members 89, 90 can be established in a number of other ways, for example, by grooving, by serrations similar to those shown at 22 in FIG. 1, by keys, wedges and/or the like. It is also clear that the couplings of FIGS. 1-4 can be utilized with equal advantage to establish rigid but readily separable connections between solid structural elements. In other words, and referring to FIG. 4, the element 87 can be a solid piece of wood, metal or plastic which is merely fonned with an internal open-ended chamber or compartment just large enough to accommodate the members 89, 90 and 96, 97. Also, it suffices if the element 88 is formed with a relatively shallow recess adjacent to the opening 108 and just deep enough to permit entry of the hooks 98. 99.

FIG. 5 illustrates a further coupling serving to connect two hollow or partially hollow structural elements 114, 115. These elements are similar to the elements 1, 11 of FIG. 1. The coupling comprises two clamping members 116, 117 and two locking members 118, 119. An actuating bolt 120 is employed to spread the locking members 118, 119 apart and to thereby move the hooks or claws 127, 128 against the innner side of an apertured end wall a of the element 115. The bolt 120 extends through openings 121, 122 respectively provided in a sidewall of the element 114 and in the clamping member 116, and meshes with the locking member 118. Helical expansion springs 123, 124 are respectively inserted between the members 116, 118 and 117, 119 to bias the clamping members 116, 117 against the adjacent internal surfaces of the element 114 and to simultaneously bias the locking members 118, 119 toward each other. When the springs 123, 124 are free to expand, a projection 125 of the locking member 118 extends into a complementary recess 126 of the locking member 119 to establish a temporary connection between the locking members. The positions of the projection 125 and recess 126 can be reversed. The projection 125 entrains the locking member 119 when the locking member 118 is shifted axially or lengthwise by way of the actuating bolts 120, for example, to withdraw the hooks 127, 128 from the element 115. The end wall 115a of the element 115 has internal surfaces 129, 130 provided with camming edges 133, 134 which cooperate with sloping conical faces I31, 132 of the hooks 127, 128 to draw the end wall 115a against the adjoining end face of the element 114 when the actuating bolt 120 is rotated in a sense to move the locking members 118, 119 away from each other.

The inner or rear end portions of locking members 118, 119 are fonned with followers 135, 136 which slide along tensioning cams 137, 138 of the clamping members 116, 117 when the locking members begin to move away from each other. The followers 135, 136 cause the clamping members 116, 117 to move in a direction to the right and to bear against the outer side of the end wall 115a.

The clamping members 116, 117 and the locking members 118, 119 are respectively provided with aligned rows of teeth 139, 140 which respectively form two paris of tensioning racks adapted to engage with each other when the locking members continue to move apart in response to rotation of the actuating bolt 120. The flanks of teeth 139, 140 are less inclined than the sloping faces of followers 135, 136. This insures that the teeth I39 engage with the respective teeth 140 when the locking members 118, 119 are moved sufficiently away from each other, i.e., the teeth 139, 140 then take over from the followers 135, 136 and relieve the pressure between these followers and the cams 137, 138. This is of advantage because the stresses developing betvVeeTr the members 116, 117 and 118, 119 are distributed uniformly along a substantial part of the overall length of the coupling. Furthermore, the teeth 139, 140 cooperate with each other in such a way that the members 116-119 are not subjected to appreciable bending or buckling stresses. It can be said that the teeth 139, 140 constitute a second tensioning device which is effective when the first tensioning device 135-138 effects a predetermined lengthwise displacement between the members 116, 117 and 118, 119 in response to continuing movement of locking members away from each other. The outer sides of clamping members 116, 117 may but need not be provided with serrations or analogous unevennesses.

FIG. 6 shows two hollow profiled structural elements 201, 202 which are connected 'to' each other by a coupling including two clamping members 203, 204 and two locking members 205, 206. The clamping members 203, 204 respectively comprise two relatively movable portions or sections 207, 208 and 209, 210 which are articulately connected to each other by rivets 211, 212 and leaf springs 213, 214. The free rear ends of springs 213, 214 extend inwardly beyond the locking members 205, 206 and are connected to each other by a rivet 215' or an analogous fatener. The springs 213, 214 are stressed in such a way that their front end portions tend to bias the locking members 205, 206 against each other, that their median portions tend to bias the front sections 207, 209 of the clamping members 203, 204 toward the adjoining internal surfaces of the element 201, and that the rear sections 208, 210 remain spaced from such internal surfaces. The sections 208, 210 engage with outwardly extending flanges or followers 205a, 206a of the locking members 205, 206; these followers extend through openings 215, 216 provided in the leaf springs 213, 214. The outer sides of the sections 207, 209 are toothed, knurled, milled or serrated, as at 217, 218, so that they can bite into the adjoining portions of the element 201. This element is fonned with an opening 2170 in registry with an opening 2180 in the clamping section 200 to permit insertion of an actuating bolt 219 which meshes with the locking member 205 and can move the locking members away from each other. The hooks 205b, 2061) at the front ends of the locking members 205, 206 then engage the inner side of an apertured end wall. 2020 of the element 202 substantially in the same way as described in connection with the preceding FIGS.

FIG. 6 shows the coupling inidle position. The hooks 205b, 206b extend into the compartment 202b of the element 202 and begin to move apart as soon as the actuating bolt 219 is rotated in a sense to move the locking members 205, 206 away from each other. The followers 205a, 206a shift the sections 207, 209 by way of sections 208, 210 so that the front end faces of the sections 207 209 bear against the outer side of the end wall 202a. As the bolt 219 continues to move the locking members 205, 206 away from each other, the followers 205a, 206a cause the sections 208, 210 to pivot toward the adjoining internal surfaces of the element 201 and to thereby press the I sections 207, 209 against the end wall 202a. Buckling of the clamping members 203, 204 is prevented by leaf springs 213, 2 14 and also because the one-piece locking members 205, 206 are then located close to the inner sides of the respective sections 207, 208 and 209, 210.

It is clear that the fastener 215' can be omitted if the leaf springs 213, 214 are integrally connected with each other or if they are fonned as a one-piece spring. Furthermore, the configuration of clamping members 203, 204, locking members 205, 206 and/or springs 213, 214 can be changed in a number of ways without departing from the spirit of my invention. For example, each of the clamping sections 208, 210 can be articulately coupled to or made integral with the adjoining locking member. Also the sections 207 209 can be fixed to or made integral with the element 201.

In this embodiment of my invention, the sections 208, 210 and followers 205a, 2060 together constitute a tensioning hooks 205b, 206b toward the"clamping members 203, 204 when the actuating bolt 219 causes the locking members 205, 206 to move away from each other. Such movement of locking members 205, 206 causes a flattening or lengthening of clamping members 203, 204, i.e., the originally arcuate or curved clamping members are caused to increase their length when the sections 208,. 210 pivot. with reference to the sections 207, 209. v

, In the embodiment of FIG. 7, two hollow structural elements 201A, 202A can be connected to each other by a coupling wherein two rigid or slightly defonnable locking members 223, 224 cooperate with a clamping unit 222 whose clamping members 220, 221 constitute two elastically deformable leaf springs. These leaf springs are integral with each other and resemble a substantially U-shpaed body provided with two tensioning prongs or cams 225, 226 which engage followers 223a, 224a at the inner or rear ends of the locking members 223, 224. The median portions of leaf springs 220, 221 form two pairs of bulges which respectively engage the internal surfaces of the element 201A and the outer sides of .the locking members 223, 224. The followers 223a, 224a extend rearwardly through a cutout 227-in the clamping unit 222, suchcutout being formed by slitting and subsequent bending of the resulting tensioning prongs 225, 226. Openings in the element 201A and leaf spring 220 permit insertion of an actuating bolt 228 which meshes with the locking member 223 and can engage the locking member 224.

The operation of this coupling is similar to that of the coupling shown in FIG. 6. The hooks 223b, 224b of locking members 223, 224 can engage that side of the wall 2028 of the element 202A which faces away from the open-ended chamber of the element 201A.

Referring now to FIGS. 8a'-8c and 9a9b, there is shown a further coupling 232 which can be utilized to establish a connection between two hollow structural elements 230, 231 so that the element 231 is normal to the element 230. FIGS.

8a, 8b and 80 respectively illustrate the coupling 232 in a starting or idle position, in an intermediate position and in a final or operative position. FIGS. 9a and 9b show two locking members 234, 233 which constitute the locking unit of the coupling 232. The clamping unit includes two elastically deformable clamping members each of which comprises two leaf springs 235, 235 and 236, 236'. The front portions 237, 238 of the locking members 233, 234 form two hooks and the rear portions of these locking members are reinforced, as at 239, 240. These reinforced rear portions 239, 240 are respectively provided with knife edges 241, 242 and with pairs of slots or grooves which respectively accommodate the rear end portions of leaf springs 235, 235' and 236, 236'. When not accommodated in the element 230, the front end portions of springs 235, 235' and 236, 236' extend away from the respective locking members 233, 234 in a manner as shown in FIGS. 9b and 9a so that they are spaced from the hooks 237 The locking members 233, 234 are respectively provided with bosses 243, 244 located between the leaf springs 235,

235' and 236, 236'; these bosses are respectively adjacent to the reinforced portions 239, 240 and extend forwardly toward the hooks 237, 238. The front portions of the bosses 243, 244 are formed with transversely extending knife edges 245, 246 respectively located at the level of knife edges 241, 242. The boss 244 of the locking member 234 has a tapped through bore to mesh with the stern of an actuating bolt 247 which extends outwardly through an opening 250 of the element when the coupling 232 is loosely inserted into the open- I ended chamber of the element 230, the reinforced end portions 239, 240 of the locking members 233, 234 are hingedly or pivotally coupled to each other. The front ends of the leaf springs 235, 235 and 236, 236 bear against the internal surfaces of the element 230 and maintain the hooks 237, 238 close to each other (FIG. 8a). The articulate device composed of two pairs of abutments which-urge the connection between the reinforced end portions 239, 240 is established by transversel T'eTtending semicylindrical fulcra 249 provided on the locking members 233, 234 and extending into complementary sockets or flutes 248. Each fulcrum 249 extends into the socket 248 of the other locking member and can turn therein through a predetermined angle to thus permit movement of hooks 237, 238 away from each other about the common axis of the fulcra 249. The just described pivotal connection between the locking members 233, 234 was designed with a view to insure that both locking members can be machined by resorting to a single tool or to a single set of tools.

In FIG. 8a, the major part of the coupling 232 is accommodated in the open-ended chamber of the element 230. The inner sides of the locking members 233, 234 bear against each otherunder the action of leaf springs 235, 235' and 236, 236' which are stressed in response to insertion into and engagement with the element 230. The free forward ends of the leaf springs bear against the outer side of the element 231. This is achieved by shifting the locking members 233, 234 by way of the actuating bolt 247. The opening 250 in the element 230 is large or long enough to permit such sidewise displacement of the bolt 247. 7 When the operator rotates the bolt 247 to move the hooks 237, 238 away from each other, the locking members 233, 234 pivot about the common axis of fulcra 249 and assume the intermediate positions shown in FIG. 8b. The hooks 237, 238 engage the inner side of the end wall 251 of the structural element 231. The knife edges 245, 246 of the bosses 243, 244 begin to penetrate into the adjoining surfaces of the element 230 to therebyarrest the locking members 233, 234 against lengthwise displacement with reference to the element 230. The leaf springs 235, 235' and 236, 236 undergo gradually increasing deformation (compare FIGS. 8a and 8b).

The operator then continues to rotate the actuating bolt 247 so as to move the locking members 233, 234 to the positions shown in FIG..8c. The reinforced portions 239, 240 of the locking members are spaced from each other, i.e., each fulcrum 249 is remote from the respective socket 248. The leaf springs 235, 235' and 236, 236' are subjected to maximal deforming stresses and bear against the end wall 251 to thereby cooperate with the hooks 237, 238 in maintaining the element 230 in a fixed position with reference to the element 231. The knife edges 241, 242 have penetrated into the element 230. The axis of the actuating bolt 247 makes with the element 230 an acute angle during movement of the locking members 233, 234 from the starting positions of FIG. 8a to the final positions of FIG. 8c, but such axis is normal or nearly normal to the element 230 in the positions shown in FIGS. 8a and 80. In FIGS. 8a-9b, the rear end portions of springs 235-236 and the reinforced portions 239, 240 together constitute a tensioning device which urges the hooks 237, 238 toward the leaf springs when the actuating bolt 247 moves the locking members 233, 234 from first positions (FIG. 8 a) toward second positions (FIG. 80).

In each of the illustrated embodiments, the actuating bolt merely serves as a means for moving the locking members with reference to each other. Therefore, this actuating bolt need not be supported by the respective structural element and/or by the clamping unit of the corresponding coupling. Consequently, the openings or passages provided for the actuating bolt in the corresponding structural element and in the adjoining clamping member need not be machined with a high degree of precision and the areas of such openings can be readily selected in such a way that the entire coupling can be withdrawn into or partially expelled from the element in which the major part of the coupling is accommodated prior to connection to the other element. It is further clear that the improved coupling can be used to connect two or more structural elements of circular or oval outline and/or to connect an element of substantially circular outline with an element of polygonal outline. In other words, the coupling can be used for connection of rods, bars, tubes, sleeves, cylinders, pipes or the like. The clamping members are then preferably provided with convex outer faces so that they can be properly fitted into a chamber of substantially circular outline". I

Another important advantage of the improved coupling is that it can be inserted into a structural element at the locale of sue so that elements -to be connected thereby can be transported in dismantled condition. All that is necessary to provide one of the elements with an aperture which can permit passage of hooks at the forward ends of the locking members and to further provide such one element with a wall (such as the wall 10 of FIG. 1) which can be engaged by the hooks in response to movement of corresponding locking members with reference to each other. The coupling can be inserted into the other element (e.g., the element 1 of FIG. 1) at the manufacturing plant or at the locale of use. If the hollow structural element 11 of FIG. 1 does not have an end wall 10, an apertured end wall can be affixed thereto by resorting to rivets, screws, nails or other types of fasteners. Furthermore, the end portion of the element 11 shown in FIG. 1 (or of the corresponding elements shown in FIGS. 28c) can be of spherical or semispherical outline. As stated before, the intermediate element 62 of FIG. 3 can also resemble a cylinder, a sphere or another body of other than polygonal outline. The element 1 (or the corresponding elements shown in FIGS. 2--8c) should be provided with an open-ended internal chamber to accommodate the coupling prior to and during connection to the adjoining element. The bolts shown in FIGS. 1 to 9b constitute but one form of actuating means which can be utilized in my coupling. For example, such bolts can be replaced by suitable wedges which are forcibly introduced between the locking members. Furthermore, one can resort to eccentrics which are inserted between the locking members to move them apart in response to angular displacement from a starting position. Still further, it is possible to employ in the coupling an actuating means which includes a explosive charge adapted to be ignited by remote control (e.g., by heating) to thereby move the locking members with reference to each other. Such types of actuating means can be employed if it is desirable to omit the openings shown in the drawings for introduction and manipulation of the bolts. The locking members are then designed in such a way that they automatically remain in spaced-apart positions which they assume in response to ignition or detonation of the explosive charge. The charge can be ignited or detonated by resorting to electrical resistance heating. Encapsulated liquid gas can be used as a substitute for an explosive charge. All such modifications are so obvious that they willbe readily understood upon perusal of the preceding description without I necessitating reference to additional drawings.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

- Iclaim:

l. A coupling for establishing a connection between a structural element which is provided with an'open-ended chamber and an apertured wall adapted to be placed adjacent to the open end of the chamber so that one of its sides faces away from the element, comprising a clamping unit having two clamping members in the chamber of the structural element; a locking unit comprising a pair of locking members disposed between said clamping members and movable between first and second positions in which they are respectively located at a first and a second distance from each other, said locking members having front portions insertable through the apertured wall in the first positions and overlying the one sidewf the wall in the second positions thereof; actuating means for movingthe locking members between said positions; and tensioning means provided ,on said members to urge said front portions toward said clamping members in response to movement of locking members toward said second positions.

2. A coupling as defined in claim 1, wherein said tensioning means comprises cams provided on the members of one of said units and followers provided on the members of the other unit and each engaging with one of said cams during at least a portion of movement of said locking members toward second positions. v

3. A coupling as defined in claim I, wherein said tensioning means are at least slightly spaced from said front portions.

4. A couplingas defined in claim 1, wherein at least one member of at least one of said units is defonnable and undergoes deformation in response to movement of locking members toward said second positions.

5. A coupling as defined in claim 4, wherein said deformable member is one of said clamping members.

6. A coupling as defined in claim 1, wherein said tensioning means comprises abutments pairs of abutments provided on each of said clamping members and the adjoining locking members.

7. A coupling as defined in claim 2, wherein said tensioning means comprises sloping cam faces.

8. A coupling as defined in claim I, wherein the members one of said units are of arcuate shape in the first positions of said locking members and consist of deformable material so that they can undergo deformation and flatten out in response to movement of locking members toward said second positions. 7

9. A coupling as defined in claim 1, further comprising fastener means connecting said clamping members to each other so that both said clamping members can be inserted into the structural element as a unit.

10. A coupling as defined in claim 1, further comprising means for connecting said locking members to each other, at least in the first positions thereof, so that the thus connected locking members can move as a unit with reference to the structural element.

11. A coupling as defined in claim 1, wherein the members of at least one of said units are integral with each other.

12. A coupling as-defined in claim 1, further comprising means for biasing at least one of said locking members to first position.

13. A coupling as defined in claim 12, wherein said biasing means comprises resilient elements each interposed between one of said locking members and one of said clamping members.

14. A coupling as defined in claim 1, wherein said tensioning means'comprises first groups of teeth provided on said clamping members and second groups of teeth provided on said locking members, each second group of teeth engaging one first group of teeth at least during a portion of movement of said locking members to second positions.

15. A coupling as defined in claim 14, wherein said tensioning means further comprises cooperating cams and followers provided on said locking members and the adjoining clamping members, said'followers being disengaged from the respective cams in response to engagement between said first and second groups of teeth.

16. A coupling as defined in claim 1, wherein said clamping members are provided with unevennesses which bear against the structural element at least in response to movement of locking members to said second positions.

17. A coupling as defined in claim 1, wherein at least one of said clamping members is fixed to the structural element.

18. A coupling as defined in claim 1, wherein at least one of said clamping members is integral with the structural element.

19. A coupling as defined in claim 1, wherein said clamping members comprise front portions which bear against the apertured wall in the second positions of said locking members.

20. A coupling as defined in claim 19, wherein the front portions of said clamping members are flush with the open end of the chamber in the structural element in the second positions of said lockin members. 1

21. A coupling as efined in claim 19, wherein the front portions of said clamping members extend beyond the open end of the chamber in the structural element in the second positions of said locking members.

' 22. A coupling as defined in claim I, wherein said actuating means comprises an actuating member which is accessible, through an opening in the structural element.

23. A coupling as defined in claim 1, wherein said actuating means comprises an externally threaded actuating member which meshes with one of said locking members and is rotatable to thereby move the other clamping member away from said one clamping member.

24. A coupling as defined in claim 1, wherein said actuating means comprises an explosive charge which can be set off by heating to thereby move the locking members to said second positions.

25. A coupling as defined in claim 1, wherein said front portions are arranged to extend through a rounded aperture of the wall in first positions of said locking members.

26. A coupling as defined in claim 1, wherein the clamping members have convex outer faces so that they can be fitted into a chamber of substantially circular outline.

27. A coupling as defined in claim 1, wherein said clamping members have concave front face adapted to engage a convex second side of the wall in the second positions of said locking members.

28. A coupling as defined in claim I, wherein the apertured wall fonns part of an intermediate element by means of which the structural element is connectable with at least one second structural element.

29. A coupling as defined in claim 28, wherein the intermediate element is a body of circular or polygonal outline. 

1. A coupling for establishing a connection between a structural element which is provided with an open-ended chamber and an apertured wall adapted to be placed adjacent to the open end of the chamber so that one of its sides faces away from the element, comprising a clamping unit having two clamping members in the chamber of the structural element; a locking unit comprising a pair of locking members disposed between said clamping members and movable between first and second positions in which they are respectively located at a first and a second distance from each other, said locking members having front portions insertable through the apertured wall in the first positions and overlying the one side of the wall in the second positions thereof; actuating means for moving the locking members between said positions; and tensioning means provided on said members to urge said front portions toward said clamping members in response to movement of locking members toward said second positions.
 2. A coupling as defined in claim 1, wherein said tensioning means comprisEs cams provided on the members of one of said units and followers provided on the members of the other unit and each engaging with one of said cams during at least a portion of movement of said locking members toward second positions.
 3. A coupling as defined in claim 1, wherein said tensioning means are at least slightly spaced from said front portions.
 4. A coupling as defined in claim 1, wherein at least one member of at least one of said units is deformable and undergoes deformation in response to movement of locking members toward said second positions.
 5. A coupling as defined in claim 4, wherein said deformable member is one of said clamping members.
 6. A coupling as defined in claim 1, wherein said tensioning means comprises abutments pairs of abutments provided on each of said clamping members and the adjoining locking members.
 7. A coupling as defined in claim 2, wherein said tensioning means comprises sloping cam faces.
 8. A coupling as defined in claim 1, wherein the members of one of said units are of arcuate shape in the first positions of said locking members and consist of deformable material so that they can undergo deformation and flatten out in response to movement of locking members toward said second positions.
 9. A coupling as defined in claim 1, further comprising fastener means connecting said clamping members to each other so that both said clamping members can be inserted into the structural element as a unit.
 10. A coupling as defined in claim 1, further comprising means for connecting said locking members to each other, at least in the first positions thereof, so that the thus connected locking members can move as a unit with reference to the structural element.
 11. A coupling as defined in claim 1, wherein the members of at least one of said units are integral with each other.
 12. A coupling as defined in claim 1, further comprising means for biasing at least one of said locking members to first position.
 13. A coupling as defined in claim 12, wherein said biasing means comprises resilient elements each interposed between one of said locking members and one of said clamping members.
 14. A coupling as defined in claim 1, wherein said tensioning means comprises first groups of teeth provided on said clamping members and second groups of teeth provided on said locking members, each second group of teeth engaging one first group of teeth at least during a portion of movement of said locking members to second positions.
 15. A coupling as defined in claim 14, wherein said tensioning means further comprises cooperating cams and followers provided on said locking members and the adjoining clamping members, said followers being disengaged from the respective cams in response to engagement between said first and second groups of teeth.
 16. A coupling as defined in claim 1, wherein said clamping members are provided with unevennesses which bear against the structural element at least in response to movement of locking members to said second positions.
 17. A coupling as defined in claim 1, wherein at least one of said clamping members is fixed to the structural element.
 18. A coupling as defined in claim 1, wherein at least one of said clamping members is integral with the structural element.
 19. A coupling as defined in claim 1, wherein said clamping members comprise front portions which bear against the apertured wall in the second positions of said locking members.
 20. A coupling as defined in claim 19, wherein the front portions of said clamping members are flush with the open end of the chamber in the structural element in the second positions of said locking members.
 21. A coupling as defined in claim 19, wherein the front portions of said clamping members extend beyond the open end of the chamber in the structural element in the second positions of said locking members.
 22. A coupling as defined in claim 1, wherein said actuating means comprisEs an actuating member which is accessible, through an opening in the structural element.
 23. A coupling as defined in claim 1, wherein said actuating means comprises an externally threaded actuating member which meshes with one of said locking members and is rotatable to thereby move the other clamping member away from said one clamping member.
 24. A coupling as defined in claim 1, wherein said actuating means comprises an explosive charge which can be set off by heating to thereby move the locking members to said second positions.
 25. A coupling as defined in claim 1, wherein said front portions are arranged to extend through a rounded aperture of the wall in first positions of said locking members.
 26. A coupling as defined in claim 1, wherein the clamping members have convex outer faces so that they can be fitted into a chamber of substantially circular outline.
 27. A coupling as defined in claim 1, wherein said clamping members have concave front face adapted to engage a convex second side of the wall in the second positions of said locking members.
 28. A coupling as defined in claim 1, wherein the apertured wall forms part of an intermediate element by means of which the structural element is connectable with at least one second structural element.
 29. A coupling as defined in claim 28, wherein the intermediate element is a body of circular or polygonal outline. 